The present invention relates to a multi-level apartment type three-dimensional water tank composed of modular glass water tanks mounted in four surfaces in front, rear, left and right directions in a plurality of layers, aimed at intensive breeding and management of various fish species providing adequate breeding environment for each fish species. In addition, a water tank sill support is mounted at a lower part of each modular glass water tank configuring the multi-level apartment type three-dimensional water tank in order to stably fix each modular glass water tank to the multi-level apartment type three-dimensional water tank. And the present multi-level apartment type three-dimensional water tank is equipped with an aquaponics system wherein culture water used for aquaculture is recycled as nutrient water for plants.
In line with development of aquaculture technologies, fish breeding technologies using land based water tanks instead of fish farms in the sea are current in use and further aquaculture in an enclosed establishment in urban area appear wherein a variety of fish and crustaceans species are separately cultured in each layer and each water tank in an establishment.
In general, the aquaculture using seawater is divided into inland water tank type and offshore fish farm type. The inland water tank type is to transfer target organisms from the sea to the land-based water tank which can be artificially controlled in its habitat where the organisms are probably exposed to more natural and unpredictable conditions. Meanwhile, the offshore fish farm type is to grow target organisms in offshore installations such as floating cages or netting built in a natural body of seawater.
When the fishery or shellfish are grown in floating cages in the sea since the time that they are still whitebait or spat, the time for them to be exposed to the risk of natural disasters becomes longer, dropping the yield. So the recent trend is that the whitebait or spat is cultured in land-based aquacultures until they grow in a predetermined size in a highly populated condition, and then they are transferred to floating cages in the sea to grow further into adult organisms with more commercial values.
With this purpose, land-based aquaculture is equipped with culture water supply and drainage facilities, treatment facilities, and oxygen supply facilities in order to create an optimal environment for the growth of marine species in a predetermined size so as to protect marine species.
On the other hand, the water tank used for the high density aquaculture is to be designed as a multi-layer structure basically, wherein the material of the tank is synthetic resin or glass rather than concrete in order to use limited breeding area efficiently.
However, the use of glass or synthetic resin like acrylic, which is basically thin, as a material of the water tank makes it difficult to design the water tank bottom portion on which a water discharging apparatus composed of interior and outer pipes for adjusting water level of culture water is to be mounted. The multi-layer structure currently is composed of separate compartments in a layer having the same environment so that one or two species can be cultured therein.
Therefore, there is a need for a tank system which is equipped with tank compartments in a plurality of layers for using the plurality of layers efficiently, wherein a variety of aquaspecies can be accommodated and the environment for the species in each compartment can be controlled to be suitable for the species.
On the other hand, supply and drainage of culture water in multi-level apartment type three dimensional water tank is made in such a way that new culture water is supplied and discharged. Since high density population of fish species are accommodated in a tank, as time elapses, nutrients such as phosphorus and nitrate flow in causing eutrophication resulting that culture water quality is deteriorated and a lot of costs is needed to deal with it. In practice, due to the lack of normal wastewater treatment facilities, wastewater is discharged into rivers and underground causing environmental pollution.
There are chemical methods and physical methods as conventional methods of improving culture water quality. In chemical methods, chemicals such as photosynthesis inhibitor, herbicides, etc. are introduced to inhibit the growth of algae and coagulants are injected to deposit sediment. However, in order to maintain the drug effect, chemicals need to be introduced periodically. And due to those chemicals, the species in fish tanks cannot grow appropriately and food safety cannot be ensured.
As one of physical methods, filtering algae with circulation of culture water by means of a filter generates a lot of costs for frequent exchange of expensive filters. As another physical method, building facilities for coagulation, sedimentation, and filtration wherein the waste is coagulated with polymer coagulant, and coagulated and precipitated debris is dehydrated in a filtration plant, requires a large area to install the facilities, considerable initial investment, and continuous operating costs.
In order to solve the problems stated above, the present invention provides multi-level apartment type three dimensional water tank in which lower parts of modular glass water tanks installed in a multi level three dimensional structure are mounted on a water tank sill support of which the upper part is open. Using the present water tank, culture water including organic material generated in fish culture is filtrated or purified in a ecofriendly manner and ecofriendly aquaponics for plant growing is also facilitated in this treatment process.